Transcript How Landforms Are Created

How Landforms
Are Created
Primary Landforms
Plate Tectonics – The earth’s surface is
broken up into large plates that are
constantly moving and bumping into one
another. Landforms created by tectonic
activity are called primary landforms.
Tectonic plates are huge slabs of rock that float on
liquid rock just below the earth’s crust. They
move but often in different directions. Continents
and oceans sit on these huge plates.
About 225 million
years ago, all of the
Earth’s landmasses
were joined into one
landmass called
Pangaea. As time went
on, the continents
separated and moved
to their current
locations.
Divergent plate boundaries are areas where
two plates move away from each other. As
they move apart, new crust is formed by
magma that is pushed up.
Mid-Atlantic Ridge
Convergent and Transform plate boundaries
occur when tectonic plates push against
each other.
Convergent plate boundaries can occur
when two continental plates push against
each other. This collision produces high
mountain ranges.
Convergent plate boundaries also occur when a
continental plate and an ocean plate move
against each other. Because the continental
plate is thicker, it slides over the thinner ocean
plate. The downward force of the lower plate
causes molten rock to build up. Then, as
magma, it erupts to form volcanic mountains.
Sometimes two plates do not meet head-on but
move alongside each other. This creates a
Transform plate boundary or fault. Violent
earthquakes can occur near these faults.
Secondary Landforms
Landforms that are formed from the broken
down remains of primary landforms are
called secondary landforms. Primary
landforms become secondary landforms
through the process of erosion.
Erosion
• Water is the most common force that erodes and
shapes land
• Glaciers are large rivers of ice that have the force
to move tons of rock.
• Wind can lift soil and carry it great distances and
deposit it in dunes, and winds that carry sand can
wear down rock.
Examples of Primary and
Secondary Landforms
Mountains are primary landforms because they are
created by tectonic activity. Over time, these
mountains can be worn down by erosion to become
hills. These hills would be secondary landforms.
Erosion
Primary Landform
Secondary Landform